VIC
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Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Murrindal, Vic, 1996 VIMP Survey (GSV3060) survey were acquired in 1995 by the VIC Government, and consisted of 15589 line-kilometres of data at 200m line spacing and 80m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
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Tectono-geomorphic landscape features in Australia, many of which are neotectonic, can be interpreted in the context of long-term patterns of large earthquake occurrence, and used to inform contemporary earthquake hazard science. Such features often represent our only means of defining seismic source parameters such as fault slip-rate, large earthquake recurrence and magnitude. They therefore provide an avenue for extending the short historic catalogue of seismicity to timeframes commensurate with the slow strain accumulation rates characteristic of intraplate environments (Clark et al., 2012). In addition to supporting seismic hazard assessment, an analysis of tectono-geomorphic landscape evolution might also be used to inform studies in a range of other disciplines. Here we present the example of the Avonmore Scarp in the Campaspe River valley of north-central Victoria, a tectono-geomorphic (and neotectonic) feature which has implications not only for seismic hazard in central Victoria, but also for mineral and groundwater resources.
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In April 2015 Geoscience Australia (GA) acquired 908 km (full-fold) Gippsland Southern Margin Infill 2D Seismic data using Gardline's M/V Duke. The survey is designed to better resolve the Foster Fault System and provide better integration between the GDPI10 survey and the existing surveys in the central deep. The data underwent pre-stack depth migration with a deghosting algorithm during processing. The dataset includes intermediate processing products as well as final preSTM and preSDM and associated velocities.
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This suite of products contains topographical relief generated from raw LiDAR data and covers the Southern extent of the Murray Darling Basin within the proximity of the Murray River. LiDAR (Light Detection and Ranging) is an airborne remote sensing technique for rapid collection of terrain data. The sensor used for this LiDAR project collected XYZ and Intensity data for 2 returns, first and last (ground) return by bouncing a pulse from the aircraft to the surface that enables the height and intensity values to be calculated. Height data within the first and last return raw LiDAR data was processed into 1m pixel DEMs. The intensity data with the first return raw LiDAR data was processed into a 1m pixel intensity image. The 1m cell size products, due to their large file sizes, are stored as 2km by 2km tiles to help facilitate data management and processing. The complete study area, covering 1.7million hectares, contains 5,288 of these tiles. All the above derived products were initially created as value added products by the Land Information Group (LIG), of the Department of Sustainability and Environment (DSE), Victoria. This acquisition was commissioned by Murray Darling Basin Commission (MDBC) and participating Consortium members including: Barmah Millewa Forum Murray Irrigation Limited, NSW Department of Infrastructure, Planning and Natural Resources - Deniliquin North Central Catchment Management Authority (CMA) Department of Urban Affairs and Planning, NSW Goulburn Broken CMA, Vic North East CMA, Vic
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Several belts of poorly-exposed igneous rocks occur in the Grampians-Stavely Zone of western Victoria, close to the interpreted Cambrian east Gondwana continental margin. Previous geochemical studies on the outcropping igneous rocks around Mount Stavely, Mount Dryden and in the Black Range have recognised characteristics similar to those found in modern magmatic arcs. These rocks are collectively considered to form part of a single Middle to Late Cambrian arc system, referred to as the Stavely Arc. While outcropping examples of the Stavely Arc magmas are well studied, the character of other (likely) arc-related rocks imaged by magnetic data beneath recent, thin cover has remained enigmatic. New geochemical data from a recent stratigraphic drilling program, together with analysis of rocks from government and industry drill holes has allowed for a more complete understanding of the Stavely Arc package. A range of rock associations have been recognised, including low-Ti boninite-like rocks, back-arc-related tholeiitic rocks, adakitic porphyry intrusives, serpentinites, and highly-depleted mafic to intermediate volcanics and intrusives. The majority of arc-related rocks comprise low- to high-K calc-alkaline basalt, andesite, dacite, and geochemically-related quartz diorite, which display similar N-MORB-normalised trace element patterns, LREE-enriched REE patterns and moderately evolved to weakly juvenile Nd isotopic compositions (Nd 500 Ma = -3.95 to +0.46). High-Al basalts intersected during stratigraphic drilling also show weakly-developed calc-alkaline compositions. However, these are distinguished from the other calc-alkaline rocks by higher Al2O3, N-MORB-like trace element patterns, relatively flat REE patterns and much more juvenile Nd isotopic compositions (Nd 500 Ma = +4.73 to +6.33). High-Al basalts are spatially associated with boninites intersected by mineral exploration drilling. The earliest geochronological evidence for Stavely Arc magmatism is provided by an isotopically juvenile felsic intrusive with an interpreted arc-related origin dated at ~510 Ma. This age is synchronous with tholeiitic dolerite from the western Grampians-Stavely Zone interpreted to have been emplaced in a back-arc extensional setting. Available ages for volcanic rocks of the Stavely Arc are only known from the Mount Stavely Belt, and show that arc magmatism reached maturity around ~505-500 Ma. Overall geochemical systematics suggest that the majority of calc-alkaline rocks of the Stavely Arc have affinities with modern island arcs with (limited) continental crust involvement. It is unlikely that the thickness of any pre-existing Precambrian crust was great, given the Nd isotopic compositions and lack of inherited Mesoproterozoic or older zircons. In comparison, the more juvenile isotopic characteristics, weakly-developed subduction-related features, and spatial association with boninites of the high-Al basalts are more consistent with a more primitive arc setting, and may represent an (early?) phase of Stavely Arc magmatism in which there was insignificant crustal involvement. Similar geochemical characteristics, ages, and inferred tectonic setting are consistent with the Stavely Arc forming part of a larger Middle to Late Cambrian arc system that also includes the Mount Wright Arc in New South Wales and the Jamison Volcanic Group (Selwyn Block) in central Victoria.
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This presentation will provide an overview of geological storage projects and research in Australia.
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Compilation of new and existing data can be used to show systematic variations in initial ore-related Pb isotope ratios and derived parameters for the Lachlan and Delamerian orogens of southeast Australia. In addition to mapping tectonic boundaries and providing genetic context to mineralising processes, these variations map mineralised provinces at the orogenic scale and can provide vectors to ore at the district scale. In New South Wales and Victoria, mapping using a parameter termed the 'Lachlan Lead Index' (LLI), which measures relative mixing between crustal- and mantle-derived Pb using the curves of Carr et al. (1995, Economic Geology 90:14671505), clearly demarcates the boundary between the Eastern and Central Lachlan provinces, and seems to identify boundaries between zones within the Western Lachlan Province of Victoria. The LLI also maps the extent of the isotopically juvenile Macquarie 'Arc' in New South Wales. However, rocks in the Rockley-Gulgong Belt, initially mapped as part of the Macquarie Arc, have a more evolved isotopic character, suggesting that these rocks are not part of the Macquarie Arc. This interpretation supports recent mapping that casts doubt on the attribution of this belt to the Macquarie Arc (Quinn, et al., 2014, Journal of the Geological Society of London 171:723736). The LLI has also identified small exposures of Ordovician volcanic rocks, well removed from the main Macquarie Arc, as possible correlates to this arc, with potential to host porphyry and epithermal deposits. Metallogenically, porphyry Cu-Au deposits in the Macquarie Arc are characterised by juvenile Pb. In contrast, Sn and Mo deposits in the Central Lachlan Province (i.e., the Wagga tin belt) are characterised by highly evolved Pb even though these deposits formed over 30 million years. Moreover, the Pb isotope data suggest that the original interpretation that copper deposits in the Girilambone district are volcanic-associated massive sulfide deposits was correct and that these deposits formed in a back-arc to the Macquarie Arc at ~480 Ma. In the Mount Read Volcanics of western Tasmania, all deposits appear to cluster along the same growth curve. However, when divided according to age (i.e., Cambrian (~500 Ma) versus Devonian (~360 Ma)), spatial patterns are visible in 206Pb/204Pb data. For Cambrian deposits 206Pb/204Pb decreases overall to the southeast, although low values are also present in the far south (i.e., Elliott Bay) and northeast. The most highly mineralised central part of the belt seems to be broadly associated with the zone of highest 206Pb/204Pb. Variations in 206Pb/204Pb for Devonian deposits broadly mimic the patterns seen for the Cambrian deposits. More importantly, a district-scale pattern in 206Pb/204Pb is present in the Zeehan district. Isotopically, the Sn-dominated core of the Zeehan district (e.g. Queen Hill and Severn deposits) is characterised by high 206Pb/204Pb, which decreases outward into the Zn-Pb-Ag-dominated peripheries. Lead isotope distribution patterns can potentially be used as an ore vector in this and other intrusion-centered mineral systems.
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Based on calcareous nannofossil evidence, the stratigraphically important interval with Hantkenina (H.) alabamensis primitiva Cushman and Jarvis in the upper Eocene of southern Australia is placed high in the foraminiferal Zone P. 16 of the tropics; previously it was correlated with the upper part of Zone P. 15. Consequently, the upper Eocene sediments above this interval at Browns Creek (Otway Basin) and Blanche Point (St Vincent Basin) are considered to represent an expanded section, with a very high rate of sedimentation. This is consistent with, and probably helps understanding of, the disjunct vertical distribution of several foraminiferal species reported previously in these sediments - particularly at Browns Creek.
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The results of a source rock study of the Bass Basin by the Bureau of Mineral Resources (BMR) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), with emphasis on the Eastern View Coal Measures, have been used in an evaluation of the petroleum potential of the basin. Geochemical analyses, including pyrolysis by the Rock-Eval method, were carried out on 29 core samples from 11 wells. Vitrinite reflectance determinations were made for each sample, and descriptions of organic matter on selected samples. The vitrinite reflectance determinations, in common with those made by previous workers, and the geothermal gradients indicate that, with the exception of Cormorant No. 1, none of the wells is deep enough to have penetrated a mature source rock section. The deeper wells in the basin centre, and wells on the southwest flank in the vicinity of the Pelican field, appear to have been terminated just above the zone of initial hydrocarbon generation. The analytical results for samples from the Eastern View Coal Measures indicate a good source potential for the Paleocene to Early Eocene (Lower M. diversus palynological zone) section, both in the deep basin and on the flanks, and a more variable, but fair to good, potential for the overlying Early to Late Eocene section. Kerogen type was determined microscopically in samples from only four wells: Bass No. 3, Aroo No. 1, Poonboon No. 1, and Cormorant No. 1. The samples were found to contain predominantly gas-prone kerogen, in keeping with the interpreted delta-plain depositional environment, although minor, more oil-prone kerogen was also detected. The study has confirmed the occurrence of potential source rocks in both the Upper and Lower Eastern View Coal Measures, but indicates that the best potential is in the Paleocene to Early Eocene Lower Eastern View Coal Measures in which most of the hydrocarbons detected to date have been located.
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Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Australia wide AFGN Absolute 2013 (P201391) contains a total of 11 point data values acquired at a spacing of 750 metres. The data is located in ACT, NSW, NT, QLD, SA, TAS, VIC, WA and were acquired in 2013, under project No. 201391 for Geoscience Australia.